“Our energy mix continues to change and National Grid adapts system operation to embrace these changes,” she added. “However, it’s important to remember coal is still an important source of energy as we transition to a low carbon system.”

Environmental groups welcomed the news. “The first working day without coal in Britain since the Industrial Revolution marks a watershed in the energy transition,” Hannah Martin, head of energy at Greenpeace U.K., said in a statement.

“A decade ago, a day without coal would have been unimaginable, and in ten years’ time our energy system will have radically transformed again,” Martin added.

In late March, the U.K. government said provisional data showed that coal output in 2016 had fallen to a record low.

The 51 percent drop in production was down to the “closure of all large deep mines, and the remaining mines producing less coal as they come to the end of their operational life.”

In addition, the government said that renewables’ share of electricity generation fell to 24.4 percent in 2016, a decrease of 0.2 percentage points compared to the previous year. Capacity for renewable energy at the end of 2016 was 34.7 gigawatts, representing an increase of 13.7 percent.